FIV is real. I am a research biologist at a veterinary vaccine company, and my colleagues in the feline virology department recently got a USDA license for an FIV vaccine for house/pet cats here in the U.S.

When I first saw news about FIV in African lions some months ago, I had a chat with the project leader about whether or not he thought it could be used in lions (our company has donated veterinary vaccines to such causes in the past). His answer was no, for a variety of reasons that I can't remember specifically but made good sense at the time.